ID-Locator separation technology is being investigated as a technology for reducing the number of paths processed by a router on the Internet backbone. A representative example of such technology is the Locator/Identifier Separation Protocol (LISP) currently being developed for standardization by the Internet Engineering Task Force (IETF). FIG. 34 is a schematic diagram illustrating an example of LISP.
LISP is provided with a core network 1 and one or more access networks (for example, access networks 2 and 3 in FIG. 34) that are connected to the core network 1. The core network 1 is provided with router, called edge nodes, that accommodates access lines from access networks. In the example in FIG. 34, an edge node 5 (LOC1) that accommodates access lines from a host 4 (ID#1) in the access network 2 and an edge node 7 (LOC2) that accommodates access lines from a host 6 (ID#2) in the access network 3 are illustrated. “ID” represents an address (IP address) used in an access network, and “LOC” (Locator: Location address) represents the address (IP address) of an edge node in a core network.
In LISP, access network addresses and core network addresses are managed separately. For this reason, in LISP, one or more management servers are provided to manage the relationships between addresses used for access networks and addresses used for core networks. In FIG. 34, a management server 8 corresponding to the edge node 5 and a management server 9 corresponding to the edge node 7 are provided. The edge node 5 registers information on the relationship between the ID of the host 4 (ID#1) and the LOC of the edge node 5 (LOC1) in the management server 8 (<1>in FIG. 34), and the edge node 7 registers the relationship between the ID of the host 5 (ID#2) and the LOC of the edge node 6 (LOC2) in the management server 9.
LISP operation will now be described with reference to FIG. 34. As an example, operation will be illustrated for the case where the host 4 transmits data to the host 6. The host 4 transmits, to the edge node 5, a packet provided with a header containing the address of the host 6 (host ID: ID#2). Upon receiving the packet from the host 4, the edge node 5 attempts to establish a tunnel to the edge node (edge node 7) accommodating a host that becomes a destination of the packet.
At this point, when the edge node 5 has not learned the address (LOC2) of the edge node 7 accommodating the destination host 6 yet, the edge node 5 transmits, to the corresponding management server 8, a message (LOC request) querying the corresponding management server 8 for the destination core network address (LOC) (as denoted by <3>in FIG. 34). Upon receiving a LOC request, the management server 8 forwards the LOC request to the management server 9 that manages the LOC corresponding to the destination address (ID#2) stored in the LOC request (as denoted by <4>in FIG. 34). The LOC request reaches the management server 9 with being transferred directly, or via a relay device (such as a router), on a control plane (C-Plane), as illustrated in FIG. 34. Upon receiving the LOC request, the management server 9 transmits a message (LOC reply) containing the address (LOC2) of the edge node corresponding to the destination host ID (ID#2), where the address is managed by the management server 9, to the edge node 5 from which the LOC request has originated (as denoted by <5>in FIG. 34). Upon receiving the LOC reply, the edge node 5 establishes an IP tunnel to the edge node 7. Subsequently, the edge node 5 generates an encapsulated packet (LISP packet) by attaching a header containing the destination edge node address (the address (LOC2) of the edge node 7) to the packet from the host 4 (user IP packet). The LISP packet is transmitted through the IP tunnel and reaches the edge node 7. The edge node 7 removes the header from the LISP packet (decapsulation), and transfers the obtained user IP packet to the host 6.
For more information, see Japanese Laid-open Patent Publication No. 2004-166089, “Locator/ID Separation Protocol (LISP) draft-ietf-lisp-10”, D. Farinacci, V. Fuller, D. Meyer, D. Lewis, Cisco Systems, Mar. 4, 2011, “LISP-DHT: Towards a DHT to map identifiers onto locators”, draft-mathy-lisp-dht-00, L. Mathy, Lancaster U, L. Iannone, O. Bonaventure, UCLouvain, Feb. 25, 2008, and “Hierarchical Mobile IPv6 Mobility Management (HMIPv6)”, H. Soliman, Flarion, C. Castelluccia, INRIA, K. El Malki, Ericsson, L. Bellier, INRIA, August 2005.